When a tubular string is pulled from a fluid filled well some fluid clings to the outer surface of the string, or pipe. The pipe is separated into selected lengths for handling and usually stands vertically on the rig floor, extending up into the derrick, until reassembled and put back into the well. The fluid drips down on the rig floor to create waste, hazard and pollution. It has, for years, been a practice to use some means to strip the fluid from the pipe surface as the string moves upward through the drilling floor and to direct the recovered fluid back to the fluid handling system.
The pipe wiper system is commonly placed below the drilling floor, and above the well head. The well head is usually fitted with a funnel opening upwardly near the wipers to gather the stripped fluid. Some pipe wipers are simple bushings of resilient material that snugly fit the pipe but are sufficiently resilient to stretch over tool joints moving upward while the bushing is tethered to the structure. Such bushings have to be removed for the passage of stabilizers and other large components of the string. Other pipe wipers have laterally movable arcuate wiper blades that can be forced against the pipe for wiping action or moved away to clear the string. Such wiper blades are resilient and shaped to overlap when against the pipe. To permit overlap, the blades are usually spaced apart vertically. Such wiper systems are usually fluid powered for opening and closing on the pipe, with the fluid power controlled by valves accessible to personnel on the rig floor.
The drill string, when suspended from the hook, usually moves laterally around the interior of the larger well head. The pipe wiper must accept this lateral movement and still perform as intended.
There is a need for a wiper system that can be opened and closed on the pipe by action of fluid power controlled by the driller, yet of such compactness that it can be installed and removed through the opening in the rig floor.
It is therfore an object of this invention to provide a pipe wiper assembly in a containing funnel, attachable to the well head, within which a wiper blade assembly can move laterally in sympathy with movement of the pipe string.
It is another object of this invention to provide a pipe wiper assembly sufficiently compact to be lowered into position, and removed, through the rotary table opening in tbe rig floor.
It is a further object of this invention to provide a pipe wiper assembly that is compact and responsive to fluid power control manipulations to open the wiper to clear the pipe string and to close the wiper to strip fluid from the pipe.
These and other objects, advantages, and features of this invention will be apparent to those skilled in the art from a consideration of this specification, including the attached claims and appended drawings.